Automatic control system for a sliding door

ABSTRACT

A sliding door is operated automatically by means of a nut and threaded rod which are driven by a reversible motor and constitute a reversible-action motion converter. The motor supply circuit comprises a switchable speed-reduction resistor, a protective resistor in series with the motor and a switchable voltage-limiter which can be connected in shunt across the motor terminals at the end of travel of the door-leaf.

' United States Patent [1 1 Graziano NOV. 11, 1975 AUTOMATIC CONTROLSYSTEM FOR A SLIDING DOOR Inventor: Charles Graziano,

Seine-Saint-Denis, France Assignee: Faiveley S.A., Saint Ouen, FranceFiled: July 12, 1974 Appl. No.: 488,490

Foreign Application Priority Data July 27, 1973 France 73.27558 US. Cl.49/28; 49/139; 49/362 Int. Cl. E05F 15/14 Field of Search 49/26-28,138-140.

References Cited UNITED STATES PATENTS 10/1918 Rosentreter 49/28 X3,104.098 9/1963 Daugirdas 49/14 FOREIGN PATENTS OR APPLICATIONS 221,4555/1959 Australia 49/26 507,803 6/1939 United Kingdom 49/28 PrimaryExaminer-Kenneth Downey Attornav, Agent, or Firm-Young & Thompson [5 7]ABSTRACT A sliding door is operated automatically by means of a nut andthreaded rod which are driven by a reversible motor and constitute areversible-action motion converter. The motor supply circuit comprises aswitchable speed-reduction resistor, a protective resistor in serieswith the motor and a switchable voltage-1imiter which can be connectedin shunt across the motor terminals at the end of travel of thedoor-leaf.

5 Claims, 2 Drawing Figures US. Patent Nov. 11, 1975 AUTOMATIC CONTROLSYSTEM FOR A SLIDING DOOR This invention relates to an automatic controlsystem for a door of the sliding motion type.

For reasons of simplicity, the following description will be essentiallyconcerned with doors of the type comprising a leaf which operates onlyin sliding motion or in other words remains substantially in the sameplane during the entire operation of the door. It should be understood,however, that the invention also applies to doors in which a slidingmovement is combined with various other movements. For example, theinvention also applies to doors having multiple leaves articulated in abellows arrangement or to doors of the type which may or may notcomprise a single leaf and operate in a movement of translation anddisengagement.

There are various known types of doors of the sliding motion type andvarious systems for controlling these doors. The invention applies todoors in which the movement is controlled in rotation by a motor and inparticular to doors of the type having at least one leaf, the slidingmotion of said leaf controlled by a nut associated with a threadedoperating rod driven in rotation by a motor which is capable ofoperating in both directions. Doors of this type are employed especiallyin public transport vehicles and in public buildings. These doors areoften required to operate automatically at a very high rate with theminimum of incidents and maintenance contingencies while satisfyingstrict conditions of safety.

In particular, at the moment of automatic closure of these doors, stepsmust be taken to ensure that users or their clothes are not liable to betrapped accidentally by the door-leaf. It is therefore necessary,without disturbing the remainder of the automatic operation, to providethe possibility of stopping the leaf upon moderate resistance, at leastover the last portion of the doorclosing travel. This enables the userto free himself without difficulty and the door-leaf can be provided forthis purpose with an elastic edge strip which may be made of rubber, forexample. It must then be ensured that the automatic movement of the leafcan be completed as initially intended.

Finally, the door-control system must be simple and economical toconstruct and to install. However, the control systems provided up tothe present time are attended by major disadvantages from the variouspoints of view which have just been mentioned.

The aim of the invention is to overcome these disadvantages by making itpossible to provide for a door of the sliding-motion type a controlsystem which offers complete safety and is both economical and rugged aswell as being easy to mount and to maintain.

The invention is directed to an automatic control system for asliding-motion door having at least one leaf rigidly fixed to a nutassociated with a threaded operating rod driven in rotation by areversible motor associated with an elastic coupling system which isdeformable in rotation; the supply circuit of the motor comprises aspeed-reduction resistor which can be changed-over by means of a switchcontrolled by the displacement of the door-leaf.

In accordance with the invention, the system aforesaid is characterizedby the combination of the following particular features: the supplycircuit of the motor comprises a protective resistor permanently mountedin series with the motor, and a voltage limiter which can bechanged-over by means of a second switch controlled by the displacementof the door-leaf so as to connect the voltage limiter in shunt acrossthe motor terminals at the end of the travel of the door-leaf, the nutand the threaded operating rod being such as to constitute areversible-action motion converter.

As is explained below, the combination of the abovementioned featuresmakes it possible to avoid the costly and complicated installation ofend-of-travel switches which have to operate repeatedly at the fullcurrent intensity of the motor. The motor is permitted to remain at lowvoltage when stationary.

The longitudinal force applied to the door-leaf can thus be also limitedby making a consequent selection of values of the elements of theelectric supply circuit. This makes it possible to prevent any bodilyinjury during closure since the driving torque on the operating rod hasthen decreased to a considerable extent. If the motor has been stoppedprior to the normal end of travel of the door-leaf, said leaf can thencontinue its automatic closing movement if so required, this beingachieved by virtue of the elastic coupling system and the permanentmotor torque.

Further properties and advantages of the invention will become apparentfrom the following description of a preferred embodiment which is givenhereinafter by way of example without any limitation being implied,reference being made to the accompanying drawing. wherein:

FIG. 1 is a general diagram of a door equipped with an automatic controlsystem in accordance with the invention;

FIG. 2 is a detailed illustration of the deformable elastic couplingsystem and the supply circuit of the motor shown in FIG. 1.

In the embodiment of FIGS. 1 and 2, the door which is equipped with theautomatic control system comprises a sliding leaf 1 rigidly fixed to anut 2 which is associated with a threaded operating rod 3. Said rod canbe driven in rotation by a reversible electric motor 4 associated withan elastic coupling system 5 which is deformable in rotation.

The motor 4 comprises a supply circuit 6 connected to the terminals 6aof a supply line by a change-over switch 6b. In the supply circuit 6, aspeed-reduction resistor 7 can be changed-over by means of a switch 8controlled by contactors 8a, 8b which are actuated as a result of thedisplacement of the door-leaf 1. This device makes it possible tomoderate the speed of the door-leaf at preselected points of its openingand closing travel.

In accordance with the invention, the device aforesaid is characterizedby the combination of the subsequently described features of the supplycircuit 6 of the motor 4 and of the motion converter constituted by thenut 2 and the threaded operating rod 3. The supply circuit 6 of themotor 4 comprises a protective resistor 11 permanently connected inseries with the motor 4 and a voltage limiter 12 which can bechanged-over by means of a second switch 13 associated with the switch 8and controlled in the same manner as this latter by the displacement ofthe door-leaf 1 so as to connect the voltage limiter 12 in shunt acrossthe terminals of the motor 4 at the end of travel of the door-leaf l.

The aforesaid combination is completed by the fact that the nut 2 andthe operating rod 3 constitute a reversible-action motion converter foractuating the doorleaf 1 in translational motion under the action ofrotational motion of the rod 3 or conversely to drive the rod 3 inrotational motion when action is produced on the door-leaf 1 so as todisplace this latter in translational motion. especially underconditions of emergency hand operation by means ofa handle 14 as isexplained hereinafter.

The operating rod 3 of ground steel, for example. has a hollowscrew-thread of trapezoid profile. In the case of a rod having adiameter of 15 to mm corresponding to doors of usual dimensions, thereis chosen by way of example a thread pitch of 60 to 120 mm which permitsboth rapid operation by the motor and easy emergency operation by handwhen making use of the handle 14. The nut 2 is a ball circuit nut andhas bearings so adjusted as to slide with the minimum friction over thecylindrical surface of the threaded rod 3.

For the emergency hand operation of the door-leaf l, a separate controldevice 15 placed within the reach of users serves to cut-off the currentsupply to the motor 4 by means of an emergency switch 16 (as shown inFIG. 2).

In the embodiment herein described by way of example, the elasticcoupling system 5 comprises a cage 21 substantially of revolution andkeyed along its axis on one end of the shaft of the motor 4. An axialrod 22 mounted on two bearings contained within the cage 2] is capableof rotating with respect to said cage and is coupled to the threaded rod3 which serves to operate the door-leaf l. The axial rod 22 which issimilar to the threaded rod 3 is provided in the same manner as thislatter with a hollow screwthread having a trapezoidal profile andassociated with a nut 23 which is similar to the nut 2 and capable ofsliding within the cage 21 without rotating.

Oppositely-acting helical springs 24a, 2417 which are mounted around theaxial rod 22 between each end of the cage 21 and the nut 24 serve tomaintain this latter substantially at the mid-length of the cage whenthe system is at rest and when the torque exerted between the motor 4and the threaded rod 3 is Zero. In fact, the motion converterconstituted by the axial rod 22 and the nut 23 is a reversible-actionconverter of the same type as the unit constituted by the threadedoperating rod 3 and the nut 2.

The strength of the springs 24a, 24b which determines the elasticity ofthe elastic coupling system 5 is chosen so as to take various operatingconditions into account as explained hereinafter.

In the supply circuit 6 of the motor 4, the values of the two resistors7, 11 as well as the value of the voltage defined by the voltage limiter12 are preferably chosen so as to ensure complete slowing-down andstopping of the motor 4 without any danger, this being achieved underthe action of the resisting torque exerted on the operating rod 3 by thenut 2 when said torque attains a value corresponding to a predeterminedlongitudinal effort on the door-leaf 1.

As will be explained hereinafter, the values and characteristicsmentioned in the foregoing are advantageously selected so as to limitthe current intensity within the stationary motor 4 to a value which issufficiently low to allow the normal operating voltage at the terminalsof the motor supply circuit to be maintained without any difficulty.

A few numerical values and characteristics thus chosen for the elementsmentioned above are given 4 hereinafter by way of example in a preferredindustrial embodiment of the invention.

The operation of the system which has just been described will now beexplained.

When the changeover switch 61) is placed in a predetermined position,the motor 4 tends to drive the elastic coupling system 5 and the rod 3so as to displace the nut 2 and the door-leaf l in the direction ofopening or closing of this latter. As the door-leaf l approaches the endof travel in the movement just mentioned. one of the contactors 8a, 8bis accordingly actuated by the door-leaf and initiates the remoteoperation of the switch 8 (as shown in FIG. 2) of the supply circuit 6of the motor 4. The switch 8 thus connects the motor 4 in series withthe speed-reduction resistor 7. At the same time. the second switch 13associated with the switch 8 connects the voltage-limiter 12 in shuntacross the terminals of the motor 4.

The device is arranged by means of a follow-up control relay (not shown)so that the above-mentioned action of the switches 8, l3 continues aslong as the control changeover switch 6b is maintained in the sameposition. The torque of the motor 4 is accordingly limited so as topermit complete slowing-down and stopping of the motor and of thethreaded rod 3 without excessive shock under the action of the resistingtorque exerted on the rod 3 by the nut 2 (shown in FIG. 1) when saidresisting torque attains a predetermined value corresponding to apredetermined longitudinal force applied to the door-leaf 1.

At the same time, the elasticity of the coupling system 5 ensuresdamping of the rotational motion of the motor 4 and of the rod 3 at theend of travel of the door-leaf l. The resultant deformation of thesprings 24a, 24b provides favorable conditions for starting of thesystem in the reverse direction by virtue of the storage of energy whichis thus acheived.

In a preferred industrial embodiment of the invention in the case ofurban transport railway vehicles, use is made of a motor 4 of commercialtype which is designed to operate normally at a direct-current voltageof 220 volts, and a running speed of 1000 revolutions per minute on lowload corresponding to a power level of the order of 250 watts.

The supply voltage at the terminals 6a is only 90 volts. The ohmicresistance of the motor 4 is 13 ohms. The resistors 11 and 7 have valuesof 15 and 62 ohms respectively. The voltage-limiter 12 which isconstituted by a Zener diode limits the voltage developed across theterminals of the motor 4 to 24 volts. This value is substantially eighttimes lower than the rated operating voltage.

In the device aforesaid and under conditions of rapid operation, themotor 4 operates at an effective voltage of the order of volts, at anintensity of approximately 0.7 amp, and at a running speed in thevicinity of 400 revolutions per minute. In the case 'of a thread pitchof 80 mm per revolution on the operating rod 3, said running speedcorresponds to a linear velocity of the order of 0.5 in per second inthe case of the door-leaf 1.

As a result of shunt-connection of the voltage-limiter 12 across theterminals of the motor 4 and the simultaneous connection of the 62-ohmspeed-reduction resistor 7 in series, the running speed of the motor 4is only revolutions per minute corresponding to a velocity of l 1 cm persecond in the case of the door-leaf l. The current intensity is then 0.7amp in the motor 4 and 0. l6 amp in the voltage-limiter l2.

When the edge of the door-leaf is applied against a door-post or againstthe opposite edge of a symmetrical door-leaf, the torque on the shaft ofthe motor 4 increases as well as the current intensity in the supplycircuit 6. However, the series resistors 7, 11 and the internal resistorof the motor 4 limit this current intensity to L0 amp, this value beingonly slightly higher than the rated current intensity. The motor 4 cantherefore withstand this stopping intensity over a long period of timewithout any difficulty.

The longitudinal force applied to the door-leaf 1 is accordingly of theorder of Kg, for example. The deformation of the springs 24a, 24b thencorresponds substantially to one-quarter of a revolution of the axialrod 22, namely mm of deflection for a screw-thread having a pitch of 80mm per revolution.

The longitudinal force applied to the door-leaf l by the motor 4 in thestationary position can be adjusted to a predetermined value byselecting in consequence the torque of the motor 4 and the thread pitchof the operating rod 3.

The system which has just been described offers a number of importantadvantages over the systems of known types.

The mechanisms and the circuit 6 of the motor 4 are particularly simple,rugged and economical. In fact, the elasticity of the elastic couplingsystem 5 facilitates start-up of the system in each direction and makesit possible to employ a motor 4 of relatively limited power which isless cumbersome and easier to maintain at a suitable temperature.Similarly, all the elements of the circuit 6 can take up relativelylittle space, taking into account the low power of the motor 4.

Moreover, since it is possible to maintain the supply circuit 6 of themotor 4 energized without any difficulty over a long period of time, itis unnecessary to provide the stopping switches and the brake systemwhich are normally employed in known systems for the purpose ofcutting-off the supply and maintaining the motor in a stationaryposition at the end of travel of the doorleaf. This advantage isimportant from the point of view of economy, overall size and enduranceof the installation.

It has been noted that the series resistors 7, 11 and thevoltage-limiter 12 which are associated with the switches 8, 13 alsomake it possible to reduce the torque of the motor 4 at a standstill.This results in a moderate value of the longitudinal force applied tothe door-leaf 1. As a precautionary measure in order to limit thedangers of even minor accidents which might conceivably arise uponclosure of the door-leaf 1, the speed-reduction contactor 8a which isactuated closure can be placed at a fairly substantial distance short ofthe stopping position of the door-leaf.

It is readily apparent that the invention is not limited to theembodiment which has just been described and many alternative forms mayaccordingly be comtemplated without thereby departing either from thescope or the spirit of the invention.

From this it follows, for example, that the elastic coupling system maybe designed in a number of different alternative forms such as inparticular a spring which works in torsion. Similarly, thevoltage-limiter 12 need not be a Zener diode but can comprise a numberof dif- 6 ferent equivalent complementary resistors connected in serieswith the motor 4.

The operation of the switch 13 of the voltage-limiter 12 can be retardedor advanced with respect to the operation of the switch 8 of thespeed-reduction resistor. This makes it possible to obtain a moreprogressive variation of the speed of the door-leaf 1, especially ifthis latter has high inertia.

What is claimed is:

1. An automatic control system for a sliding-motion door having at leastone leaf rigidly fixed to a nut associated with a threaded operating roddriven in rotation by a reversible electric motor associated with anelastic coupling system which is deformable in rotation, the supplycircuit of the motor being provided with a first switch and a secondswitch, a speed-reduction resistor which can be changed-over by means ofthe first switch controlled by the displacement of the door leaf.wherein the supply circuit of the motor includes a protective resistorpermanently mounted in series with the motor, and a voltage limiterwhich can be changedover by means of the second switch controlled by thedisplacement of the door leaf so as to connect the voltage limiter inshunt across the motor terminals at the end of travel of said door leaf,the values of the two resistors and the threshold values of the voltagelimiter as well as the characteristics of the motor being so selected asto limit the current intensity in the motor, when said motor is at astandstill, at a sufficiently low value to maintain the normal operatingvoltage at the terminals of the motor supply circuit, said nut and saidthreaded operating rod moreover constituting a reversible-action motionconverter.

2. A system according to claim 1, including an emergency control for thehand operation of the door, wherein said emergency control is associatedwith a cut-off switch on the supply line of the motor.

3. A system control according to claim 1, wherein said values of theresistors and of the voltage limiter, as well as the characteristics ofsaid reversible-action motion convertor and of said motor are selectedso as to ensure complete slowing-down and stopping of the motor underthe action of the torque exerted on the operating rod, when said torqueattains a predetermined value corresponding to a predeterminedlongitudinal force applied to the door leaf, said longitudinal forcebeing consistent with the safety of users.

4. A system according to claim 3, wherein the operating rod has adiameter of 15 to 30 mm and a thread pitch of 60 to mm, the deformationof the elastic coupling system corresponding substantially to onequarterof a revolution of the operating rod for said predetermined longitudinalforce applied to the door leaf.

5. A system according to claim 4, wherein said elastic coupling systemcomprises a cage containing a nut capable of sliding within the cagewithout rotating and an axial rod similar to said operating rod of thedoor, oppositely acting springs mounted between said cage and saidsliding nut, said cage and said axial rod being respectively coupled tothe shaft of said motor and to the

1. An automatic control system for a sliding-motion door having at leastone leaf rigidly fixed to a nut associated with a threaded operating roddriven in rotation by a reversible electric motor associated with anelastic coupling system which is deformable in rotation, the supplycircuit of the motor being provided with a first switch and a secondswitch, a speedreduction resistor which can be changed-over by means ofthe first switch controlled by the displacement of the door leaf,wherein the supply circuit of the motor includes a protective resistorpermanently mounted in series with the motor, and a voltage limiterwhich can be changed-over by means of the second switch controlled bythe displacement of the door leaf so as to connect the voltage limiterin shunt across the motor terminals at the end of travel of said doorleaf, the values of the two resistors and the threshold values of thevoltage limiter as well as the characteristics of the motor being soselected as to limit the current intensity in the motor, when said motoris at a standstill, at a sufficiently low value to maintain the normaloperating voltage at the terminals of the motor supply circuit, said nutand said threaded operating rod moreover constituting areversible-action motion converter.
 2. A system according to claim 1,including an emergency control for the hand operation of the door,Wherein said emergency control is associated with a cut-off switch onthe supply line of the motor.
 3. A system control according to claim 1,wherein said values of the resistors and of the voltage limiter, as wellas the characteristics of said reversible-action motion convertor and ofsaid motor are selected so as to ensure complete slowing-down andstopping of the motor under the action of the torque exerted on theoperating rod, when said torque attains a predetermined valuecorresponding to a predetermined longitudinal force applied to the doorleaf, said longitudinal force being consistent with the safety of users.4. A system according to claim 3, wherein the operating rod has adiameter of 15 to 30 mm and a thread pitch of 60 to 120 mm, thedeformation of the elastic coupling system corresponding substantiallyto one-quarter of a revolution of the operating rod for saidpredetermined longitudinal force applied to the door leaf.
 5. A systemaccording to claim 4, wherein said elastic coupling system comprises acage containing a nut capable of sliding within the cage withoutrotating and an axial rod similar to said operating rod of the door,oppositely acting springs mounted between said cage and said slidingnut, said cage and said axial rod being respectively coupled to theshaft of said motor and to the operating rod of the door.